Follow the moon for incredible May astronomy


The May moon meets Venus and Mercury, at twilight en route to the season of eclipses and more.

I wonder where is all the action of the solar system hiding? While the twilight sky may seem devoid of planets (with the exception of Mars), everything is about to change tonight. The motto of astronomy in May 2021 is to “ follow the moon ” as it makes several spectacular planetary passes, then kicks off the first eclipse season of the year.

First, the thin, growing crescent moon obscures the brilliant planet Venus tonight on May 12.e. While this is happening over the South Pacific and most of us will miss the event, the two will huddle very close to each other on the evening of Wednesday, May 12.e, which makes them a very photogenic pair. Ash light or light from the Earth on the dark branch of the Moon (caused by sunlight reflected from the Earth) will give the scene an overall 3D appearance.

The view of the sky at dusk on May 12, looking west. Credit: Stellarium.

-3.9 magnitude Venus will actually make a great guide on the night of May 12e to spot the thin ethereal crescent moon. Sure, Venus is tiny, at 10 “in diameter and 98% illuminated, compared to 29.5 feet in apparent diameter and 1.2% moonlight … but Venus is inherently brighter, bright enough that you can see it during the day near the sun’s greatest elongation… if you know exactly where to look in the sky. Your next chance to try this in 2021 is October 29, when Venus is 47 degrees east of the Sun and dominates the sky at dusk.

The imprint of the occultation of Venus on May 12 by the Moon. Credit: Occult 4.1.

Now, do you see this zero magnitude “ star ” above the Venus-Moon pair tonight? It is the deepest planet Mercury. In fact, Mercury is heading for one of its best appearances for northern hemisphere watchers for 2021 this month, reaching 22 degrees east of the Sun on May 17.e. After that, Mercury loses altitude night after night as Venus gains importance, until both switches are placed on the night of May 29.e, when the two planets are in the same telescopic field of view only 24 ‘apart, less than the diameter of a Full Moon.

Follow this Moon as it grows and passes 1.5 degrees of magnitude +1.6 of Mars on the evening of May 16.e.

Tonight’s first sighting of the thin crescent moon also marks the end of the fasting month of Ramadan for Muslims around the world and the start of the celebration of Eid al-Fitr. The Muslim calendar is based solely on the lunar cycle, which means that months like Ramadan move forward 11 days from the Gregorian calendar based on the sun. Other hybrid systems – such as the Hebrew or Chinese calendars – rely on both solar and lunar cycles, and therefore have to add an additional or “embolismic” month once every 2-3 years to stay in sync.

The Moon has also just passed its the most distant climax (its “ furthest point ” on Earth) for 2021 406,511 kilometers away on May 11. It also prepares us for two interesting astronomical events in the coming weeks:

The first is the May 26 total lunar eclipse. This will favor the Pacific region, with a maximum total duration of 14 minutes and 30 seconds. It also falls near the nearest perigee (the Moon’s “ closest point ” on Earth) for 2021 just 10 hours earlier, 357,309 kilometers away. No doubt the “Super-Blood Moon” meme will sweep the Internet once again.

Visibility outlook for the May 26 total lunar eclipse. NASA / GSFC / F. Espenak.

Then, two weeks later, the Moon will again be close to apogee and will be too small to cover the Sun during the June 10 annular solar eclipsee. The annularity of this eclipse will sweep across central Canada northeast of Hudson Bay, although much of northeastern North America is treated to a fine partial solar eclipse rising to the l ‘dawn.

The annular eclipse of June 10. NASA / GSFC / AT Sinclair

Can’t wait until June? If you live on the east coast of the United States, another intriguing space event could be heading skyward tonight: Watch for the launch of a NASA Wallops Black Brant XII sub-orbital rocket in Virginia, with the KiNET-X experience. The KiNETic scale energy and momentum transport experiment will release chemical barium vapor tracers approximately 10 minutes after launch, with the aim of mapping and understanding how energy transfer occurs in the earth’s upper atmosphere. These types of launches are always difficult to get off the field, as the sky is not only clear at the Wallops launch site, but also at the Bermuda tracking station downstream from the experiment. A mission similar to Wallops a few years ago took weeks to get started. Another, doubled AZURE BLUE, launched in 2019 from the Andoya Space Center in the Scandinavian High Arctic, with equally bizarre results. KiNET-X has a 40 minute launch window tonight, starting at 8:06 p.m. EDT / 12:06 a.m. GMT.

Viewing outlook for KiNET-X launch tonight. Credit: NASA / GSFC

We will tweet like @Astroguyz about these heavenly sky events, launches and more. Watch for full guides for each eclipse in the coming weeks, here on The universe today.

– Main image credit: The Moon meets Venus in 2016. Image credit and copyright: Sharin Ahmad.


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